This invention relates to a control device for a marine propulsion unit engine and more particularly to an improved system for purging cooling water from the engine when the marine vehicle is taken out of service.
It is well known that one of the operational difficulties with marine propulsion engines is that the engine may ingest a large amount of water, regardless of how well it is protected, during operation of the watercraft. That is, either an outboard or an inboard engine may receive through its induction system fairly large amounts of water. This water, if it is permitted to be retained in the engine for any period of time can be a problem, particularly where the watercraft is operating in a marine environment and the water may contain large amounts of salt.
While the engine is running, any water which may be ingested through the induction system will be vaporized by the heat of the engine and deposits present no significant problem. However, if the engine is shut off, particularly after a large amount of water may be ingested due to capsizing or the like, this water if permitted to remain in the engine can present problems of corrosion. It has, therefor, been the common practice for operators manuals to suggest running the engine for a brief period of time after the watercraft or engine is taken out of service. That is, once the water vehicle, in the case of an inboard engine craft, or the outboard motor either when attached to a watercraft or when detached from it and not in use to run the engine for a brief period of time with no coolant in the engine. Such brief running will generate sufficient heat so as to vaporize any water which may be in the engine and dispose of it. In addition, this will leave fuel and lubricant in the engine so as to avoid against corrosion.
There is, however, a problem with such running of the engine when the cooling system has been depleted of its coolant. If the engine is run too long, over heating can clearly result and damage may be encountered. On the other hand, if the engine is not run a sufficient length of time, then water vapor can still be retain in the engine and the aforenoted problems result.
It is, therefor, a principle object of this invention to provide an improved control for a marine engine so as to permit the interior of the engine to be purged from water vapor without damaging the engine.
It is a further object of this invention to provide an improved control for running an engine for a marine watercraft for a brief period of time when the engine cooling jacket has been depleted of its coolant.
In addition to the problems of having water vapor enter into the interior of the engine, it is also desirable to purge the engine cooling jacket of any liquid once the engine is being taken out of service. This is done in a manner similar to the manner for purging the interior running components from water vapor.